A Bourdon tube is a fluidic linkage used in gauges to measure pressure. The Bourdon tube is essentially a tube bent along its length into an arc of generally constant radius. In cross-section, the tube may be a roughly oval shape or have a flat inner wall and a curved outer wall. One end of the tube has a fitting that allows the inside of the tube to be connected to a source of pressurized fluid. The other end of the tube is closed. The end with the fitting also has a fixture or mount for use in attaching the tube to the gauge body. The closed end has a hook or loop for attachment to the needle of the gauge. When the pressure inside the tube is increased, the curve flattens out causing the distance between the ends to increase and the needle to move. However, the volume inside of the tube changes only very slightly, if at all. This characteristic is useful for precision gauges because it reduces or eliminates unintended reductions in pressure or increases in volume of a system being measured.